Differential diagnoses of multiple myeloma

MGUS

A M-component with < 30 g/l and < 10 % plasma cells in bone marrow biopsy which is not accompanied by symptoms, biomarkers or signs of multiple myloma or other B-lymphoproliferative disease is called MGUS (monoclonal gammopathy of undetermined significance).

The differentiation between MGUS and smouldering multiple myloma is based on the size of the M-component and/or amount of plasma cells in the bone marrow. However, there is no indication for treatment until (symptomatic) multiple myeloma is present.

MGUS is relatively common (up to 3% in people over 50). Thus, most persons having M-protein in their serum have MGUS and not cancer of the bone marrow.